1. Field of the Invention
The present invention relates to a touch sensing apparatus and a method thereof that can minimize the influence of noise and ensure a stable operation by controlling a dynamic range of a signal converting unit according to a frequency and a signal level of a driving signal applied to an electrode.
2. Description of the Related Art
Touch sensing apparatuses such as a touch screen, a touch pad, and the like, as user interface apparatuses attached to a display apparatus to provide an intuitive input method to a user, have been widely applied to a variety of electronic apparatuses such as a cellular phone, a personal digital assistant (PDA), a navigation device and the like, in recent years. In particular, recently, with the increase in demand for smart phones, the rate at which a touch screen has been adopted as a touch sensing apparatus capable of providing various input methods in a limited form factor has increased on a daily basis.
Touch screens adopted in portable electronic apparatuses may be largely classified into resistive type and capacitive type touch screens, according to a touch sensing method. Since the capacitive type touch screen is advantageous in that a life-span thereof may be relatively extended, and various input methods and gestures can be easily implemented therein, the adoption rate of the capacitive type touch screen has steadily increased. In particular, it is easier to implement a multi-touch interface in the capacitive type touch screen than in the resistive type touch screen, and as a result, the capacitive type touch screen is widely applied to an electronic apparatus such as a smart phone, or the like.
Touch screens are generally attached to a front surface of the display apparatus, while touch sensing apparatuses other than touch screens are also generally provided within the electronic apparatus. Accordingly, touch sensing accuracy may be deteriorated due to noise generated in various electronic components, e.g., a wireless communication unit, the display apparatus, and a power supply device, provided together in the electronic apparatus. In order to solve this problem, a frequency hopping method of changing a frequency of a driving electrode applied to an electrode of the touch screen according to noise generated from the outside may be adopted. However, in this case, a touch sensing error depending on an operational dynamic range of a circuit generating a digital signal through frequency conversion may occur.